Manufacture of halocarbon oils



April 28, i953 w. T. MILLER 2,636,907

MANUFACTURE ORHALOCARBON OLS Filed Feb. 5, V194,9

INVEN TOR.

WILLIAM T, MILLER a 79 nimm PRaoucr ATTORNEYS Patented Apr. 28, 1953 WilliamrTgMillenlthaca, Y., .assigner to ylhe W..Kcllogg Company, acorporation offela- 'Waffe .nppli'eationrehruary 5, 1'94'9, SerialNo. 174,809

.'.llhis invention relates to the manufacture .of

.-lralocarbons. .In one of l.its aspects this 4in-vention relates to fthe manufacture :of halocarbon oil-s of intermediate boiling range. vIn another `aspect Athis invention :relates .to the iiuorination 4of halocarhons, including .unsaturated perhalocarbone. -n one Vof :it-s ymore :particular aspects .this invention .relates :to `a fprocess for vrthepolymerization .of iperfluoro-olens and. ;per'fluoro .chloroolefins ito .produce .halocarbon oils, .greases .and waxes and the 'subsequent cracking of these Imaterials `to iproduce oils .of lower .molecular Weight l.and boiling range .followed by uorina- 4tionof ther-.cracked product. Attention is drawn to my .copending application Serial No. 720,478, `iiledJanuary 26, 194i?, which-'discloses the cracking of Apolytriluorochlomethylene oils 4.and waxes and .subsequently :.iiuorinating Vthe :cracked product `with La freehalogen or .a metal halide.

Normally .liquid .halocarbon oils may Ahe Lproduced `directly by .the polymerization .of perhalo- .oleiins .under .appropriate conditions. However,

this method :of preparing halocaroon oils results in .a product l.o'i relatively wide .boiling Another .object .of 'this invention is 'to provide .a .method'for .increasing the 4chemical and,phys

ical stability of cracked halocabons.

`A .further .object .is .tg fliuorinate unsaturated .halocarloo'n's` Another .object 'is 'to ,provide a method for "the .40

production of polytri'iiuorochloroethylene 'oils of an intermediate boilin'g range.

`Various .other .objects and .advantages .o'f 'the .present invention wvill .become apparent from Lthe accompanying .description and disclosure.

fAs herein employed, .halo'carbons .are -fdened as A.c'oi'npounds consisting substantially exclusurely of carbon fand halogen with any l.degree 4of saturation fand containing ionly negligible (Cl. .Zeil-45753) ..2 Lsaturation consi-sting of .luorine and carbon, and alperiiuorochloro-olenis defined Las a perlhalo--olen :consisting of fluorine, chlorine .and carbon. The ,peruorochloro-olens of .this .in-

5 vention'iare those vcontaining not vmorethanone chlorine atom peratomof carbon.

.1n accordance -with this invention 1a .-perhalo olefin such as ftrifluorochloroethylene, A:tetra- .Aiiuoroet'hylena Aperiiuorooutadiene, etc. is pol-y- .10 merized under conditions such that .oils .and

greases at .-normalatmosphieric tempeartures and `hard waxes havingfsofteni-ng points extending up .-to .about .200 lC. `are produced. The .product of 'the :polymerization .is separated .from unre- I1 5 acted :monomer and smayihe separatedlinto Ifractions, 4such .as oils,.greases and waxes, and rthe ,..polymerization products either singlyor "together are :polymerized or lcracked `under :appropriate conditions to split carbon-carbon .bonds where- .20 .by a ihalocarbonoil :of llower boiling range and of lower .molecular weight than the aforesaid polymerization l.product iis produced. .The cracked l.halocarhon oil is .separated ."frorn '.lower boiling `ha'locarbons and .may .he ."urther separated into "2.5 .particular fractions. vThe .halocar'loon "fractions thus produced are "fluorinated singly orin com- Abinationk with .each .other witha halogen fluoride, .such asehlorine .ti'fluorida to produce a -vnflirm'allggf 'liquid .oil .of .relatively narrow boiling 30 range Shaving .optimum chemical "and physical characteristics. .The luoination treatment 'may invlve -addition of 'fiuorine -an'dfor replacement o'f .hydrogen and lc'lilorine .with fflu'orin'e. The .oils produ-ced `by l.the process 'of "this invention 35 vgenerally"lccil within the Yrange of about -100 E. 'to vabout "250 C. 'at "1 to .2 mm. of mercury pressure .and include some high molecular'weig'ht :residues I-Iowever, oils of narrower "or wider boiling "ranges 'may "be 'produced "by this invention without departing *from the "scope thereon The 'boiling range of the oilproductwill'depend upon such factors "as 'the 'charging stock, 'condi tions o'f polymerization Vand cracking, and Avarious other factors, as 'will lh'ecome apparent ffrom the ,"following description lan-d disclosure.

Fior a "better understanding 'of the v-presezit 1invention, 'reference 4will be made 'to 'the `aecomvpany'injg drawing which -diagrainmat'ioaliy illustraites "an 'arrangement of apparatus vtor 'the -pro- 50 'duction of A'int'ei-mediate Alco'iling halo'carbon loils from the monomer, Evtritiuorochlomethylene. However, it is to r`Ice understood fthat fthe Vintegrated "proces-s as 'illustrated lin the drawing .may he "anplied to `the `production of li-ntermediate *boiling Enalocarbon foi-ls from futher monomers ani `pericaio-o'leiinfs, Zas lpreviou'siy mentioned.

The principal pieces of apparatus of the present invention comprise a polymerization chamber I2, a cracking chamber 4I and a uorinator 61 and various purification and separation equipment for purifying and separating materials utilized and produced.

According to the drawing and the process illustrated, triluorochloroethylene is the starting material and may be prepared by the dechlorination of trichlorotrifluoroethane (Freon 113) and purified in accordance with the teachings and disclosure in my prior and copending lapplication Serial No. 14,797 filed March 13, 1948, now Patent No. 2,579,437. The monomer is introduced together with an appropriate chain transfer solvent and a promoter through conduit II into polymerization chamber I2. The monomer, solvent and promoter may be introduced continuously or intermittently, 'and separately if desired, into chamber I2. Element I3 represents a suitable heating or cooling means for maintaining polymerization chamber I2 at the -desired temperature level. Numeral I4 designates a` conventional stirrer for maintaining the contents of chamber I2 in an agitated condition during the polymerization.

Polymerization is effected under liquid phase conditions by employing a sufficiently high pres- Vsure at the temperature of polymerization. The

temperature of polymerization will depend upon such factors as the particular promoter and chain transfer solvent employed and the molecular weight and boiling range of the product to be produced. In general, a suitable polymerization temperature will lie within the range of C. to 300 C., preferably between about 470 C. and about 200 C. A suitable residence time is allowed for completing the desired reaction and obtaining the desired product. The residence time will range from a matter of seconds to as much as one hundred hours, preferably between about 1 minute and about 10 hours. Excess pressures over that necessary to obtain liquid phase operations may also be used, such pressures ranging as high as 25,000 pounds per square inch gage.

Promoters which are employed comprise organic peroxides and free oxygen. Examples of suitable promoters includes acyl peroxides such as acetyl peroxide, monochloro-dichloro and trichloroacetyl peroxides, fluoroacetyl peroxides,

,benzoyl peroxide, p-bromobenzoyl peroxide, and dichlorofluoroacetyl peroxide.

Preferably for the polymerization of triuorochloroethylene to oils, benzoyl peroxide is employed at a temperature vbetween about '75 C. and about 175 C. The

weight ratio of promoter to monomer charged is `between about 1:10 to about 12200, generally being between about 1:15 to 1:50. Increasing `the amount of promoter decreases the molecuucts of the polymerization. In the process illustrated in the drawing, chloroform is employed as the chain transfer solvent.

The product produced by the polymerization has a boiling range between about 50 and about The Weight ratio of solvent- 'perature about 65 C. at atmospheric pressure,

350 C. at 1-2 mm. of mercury pressure, but the exact boilingrangerwill depend upon the various operating conditions and promoter and solvent employed. The waxes produced by the polymerization under the conditions of this invention, including hard waxes, have softening points as high as 200 C. A portion of the product will usually consist of both waxes and greases; that portion may be between about 10 and about 50 per cent by volume of the total product. Conversion as high as 50 per cent of monomer charged, or better, is possible under optimum conditions of operation.

Thermal polymerization may be employed without the use of promoters and/or chain transfer solvents but generally with small amounts of free oxygen to obtain an oil product. For thermal polymerization, relatively higher temperatures and pressures are necessary.

Polymerization products are withdrawn from chamber I2, continuously or intermittently,

through conduit I6 and passed to a stripper I8.

In intermittent operations, normally gaseous components of reaction chamber I2 are withdrawn therefrom through conduit I1. In stripper I8 unreacted monomer, chloroform, promoter residue, and relatively low boiling halo- 'carbons are stripped from the polymerization products. 'heating or cooling means for obtaining the desired bottoms temperature in stripper I8. The

Numeral I9 designates a conventional bottoms temperature of stripper I8 when polymerizing triiiuorochloroethylene is usually maintained above room temperature, usually about maintained usually at a temperature lower than the bottom temperature and preferably, when polymerizing trifluorochloroethylene, at a temdepending upon the desired materials to be lpassed overhead from stripper I8. Stripper I8 24 is maintained at a temperature of about 60 55` C. or lower. condensate and uncondensed vapors are passed from condenser 24 to accumulator 21 through conduit 26. 4

Condensate comprising the chain transfer solvent is removed from accumulator 2'I through conduit 28 and is recycled by means not shown to polymerization chamber I2. Uncondensed vapors comprising the monomer trifluorochloroethylene are removed from condenser 2'I and passed through conduit 29 to a drier 3I. Drier v 3I contains phosphorous pentaoxide or silica' gel,

or both, for the removal of hydroxy compounds from the monomer. The dried monomer vapors are passed from drier 3| to condenser 32 where the vapors are cooled to a temperature of about 27 C., at which temperature the monomer is 'condensed Condensed monomer and any uncondensed vapors are passed from condenser 32 through conduit 33 to an accumulator 34. Condensate is removed from accumulator 34 by 75.

means of conduit 36 and is recycled by means "asesinar tom thereof by means of conduit 22 and are l passed to a cracking chamber 4I Where the oils are cracked to a product of lower' boiling point and lower molecular weight. The crude halocarbon oils are passed thri`3ughu stainless' steel .coils immersed in a lead bath maintained at a temperature between about 330 and about 400 C.,

Apreferably between about 3`50" C. and about' 375 C.. at which temperature the polytrifluorochlorethylene oils and waxes are cracked, The crackingl feed may be introduced in either the vapor or liquid phase depending. on the composition and character thereof, as desired. Higher temperatures such as 600" C. `may be used for cracking without departing from the scope of this invention. At the preferred temperature range the residence time of they oil in the cracking coils' of chamber 4I will generally be between about seconds and about 2 hours, depending upon the degree of cracking desired", type of apparatusv and mannerof operation.v Crackingr of thel crudev halocarbon oils and waxes to intermediate' oil increases the yield of oil in the interfmediate boiling range in some instancesas' much as 50 per cent or more over that which could be obtained by direct polymerization.

The cracking eiiluent is passed in the vapor or liquid phase from cracking chamber t! through conduit 42 to fractionator 41, where it is introduced at an intermediate' point. A reboiler M is employed' to maintain the desired bottom temperature of fractionator it and a portion of the liquid' bottoms' product is circulated through conduit 4G and' reboiler 44 and returned to fractionator d3. Element 41 is a conventional heat eX- chang-er for maintaining the desired temperature of the reboilei' which is generally between about 200' and about 3500' C'. at a pressure about 1 2 mm. of mercury. A cooler, not shown, may be positioned on conduit :it for cooling or conlensing the inlet feed to fractionator 431 The bottoms product comprising haloc'arbon oilsv boiling above about' 250 to 350 C. is removed from fractionator 113 by means of outlet conduit 45. All or a portion of the bottoms product from fractionator 43 may be recycled to cracking chamber il by means not shown.

Numeral. i8 designates a cooling coil inthe upper portion of fractionator 43 for maintainingthe top temperature of the fractionator at the desired level, preferably between about 100 and about 300 C. An overhead vaporous fraction comprising relatively low boiling halocarbon oils and small quantities of monomer, hydrogen iiuoride andhydrogen chloride, is removed from fractionator (it and passed through conduit 5I to condenser 52. Condenser 52- is maintained at a temperature below about 100 C'. to condense substantially all of the halocarbon oils.v Condensate is passed from condenser 52 through conduit 53 to accumulator 5d. Condensate from accumuat'or bfi' comprising relatively low boiling halocarbon oils is removed from accumulator 54 through conduit 56. Av portion of this condensate may be recycled to the upper portionot fractionator i3, by means not shown, as' a reflux, or

may be recycled to cracking chamber 4I, ifY decoiii-prismg monomer, hydrogen. fluoride and' hy'- 'drogen chloride are removed-i from accumulator 54. through conduit-51 and passed to absorber 58. which contains sodium uoride. In absorber 58 hydrogenl fluoride absorbed. The remainder of" thegascous material comprising monomer and hydrogen chloridel is passed from absorber' 58 through cond-uit 50 toi absorber tl', which containscausti'c suchv as solid sodium hydroxide.- In absorber 6i hydrogen chloride is removed? from theg'ases.A The remaining gases comprising monomer and any accompanying gaseous halocarbons" are removed from absorber tl through conduit t2 by means of a partial' vacuum, and may be'recycled to reactor l it, if desired.

The iiuorocarbon oill fractions in conduits 49 and/or 5G and/or any intermediate fractions withdrawn from fractionator 43 by means not shown are now treated under i'iuorination conditions to improve the physical and chemical characteristics of these oils. These oils may be separatelyv treatedy or may be combined for treatment, as desired. In this description the' oils are combined for treatment by introduction into conduit 05 through which they are passed to ii'uorinatoi-t-i. Fiuorinator t1 comprises an elongated vertical tower' having a plurality of spaced heat exchangelmeans et, 69, 'H and i2 along. the length of the tower. The halocarbon oils to be fluorinated are introduced into the upperv portion of column iii" where the temperature is maintained between about and about' 200 C. by meansof heat exchanger through which a suitable cooling. medium is circulated at the appropriate temperature, or'in which a liquid is boiled under pres'- su're at the desired temperature to be maintained in the upper portion of iiuorinator 61. Halocar'- bon oils are passed downwardly through uorinator B? countercurrently to an upwardly flowing' stream of chlorine triiuoride introduced at the bottom of column 51 through inlet conduit '13. Preferably, column 5l is maintained under gradual increasing temperature gradients from top to bottom so that the temperature of the halocarbon oils removed from column 61 through bottom outlet conduit 'M is about 250 C., or higher. 'iiluorination may be eiected at a substantially constant temperature from top to bottom of column El without departing from the scope. of this invention. Vapors comprising unreacted chlorine triluoride, hydrogen chloride, hydrogen iiuoride, etc. are removed from the upper portion of column vi'! through conduit 76.

The iiuorinated oils from column 6.1 are passed through conduit i4 to a stripper 71. Numeral 18 designates a heat exchange means. for maintaining. the desired temperature of the oils inthe lower portion of stripper T8. Generally. in the case of polytri'luorochloroethylene oils, the temperature is maintained at 'about 100.to 250 C. Nitrogen is bubbledl through the liquid phase in stripper 'l1 by introduction therein through conduit i9. Halocarbon oils substantially completely saturated are removed from stripper 'H through outlet conduit 8.! as the product of the process. This oil product may be further separated into ilesired fractions. such as by fractional distillaion.

Stripped chlorine trifluoride together with any hydrogen chloride, hydrogen -uoride and free iiuorine and chlorine obtained by stripping the fluorinated oils are removed fromv the upper portion of stripper 'Il through outlet conduit 82- and are combined with the vapors in conduit 16. The combined vapors are passed to a combustion a pressure of 25 millimeters.

chamber 83 in which any free fluorine and chlorne are burned with hydrogen. .Hydrogen is in- ,troduced into combustion chamber 83 through conduit S5. The combustion effluent comprising acidic compounds is removed from chamber 83 and passed to the lower Iportion of a caustic scrubber 84 in which vapors are passed upwardly countercurrent to a downwardly flowing caustic solution, such as an aqueous solution of sodium hydroxide. Rich scrubbing solution is removed from caustic scrubber 84 through outlet conduit ,81. A portion of the rich scrubbing solution .may be withdrawn and another portion recycled through conduits 88 and 36 to the upper portion of scrubber 84. Fresh caustic solution is introduced into scrubber 84 through conduit 85. Vapors substantially free from acidic compounds areremoved from caustic scrubber 84 through conduit 39 by means of a -partial vacuum.

EXAMPLE fr Chloroform, triiiuorochloroethylene and benzoyl peroxide (wet-10% water by weight) were introduced into a steam jacketed reaction bomb of stainless steel equipped with a stirrer. The weight ratio of monomer to chloroform was about 2:3 and the amount of peroxide based on the monomer charge was aboutv 6 per cent by weight. The temperature was held at 212 C.

for about six hours and the initial pressure was about 20G-255 pounds per square inch gage and decreased to 90 pounds per square inch gage at the end of the six hour period. After the polymerization was completed the pressure was released from the reaction bomb and it was held at a temperature of about 40 to about 50 C. to remove unreacted monomer. The temperature was then raised to about 100 C. to remove chloroform. The temperature was then raised to about 160 C. at a vacuum of about 53 cm. of mercury to remove inal traces of monomer and chloroform. A

The yield of polymer based on the monomer charged was about 90 per cent and had the consistency of soft wax at room temperature. Polymer prepared in the above manner was charged to a conventional vacuum distillation apparatus for cracking. The distillation still was raised to a temperature of about 150 C. at 288 millimeters of mercury pressure. The vapor temperature during this period of operation was about 45 C. As the distillation was continued, the pressure was decreased to about 0.5 millimeter of mercury with a corresponding increase in still temperature to about 210 C. and a Vapor temperature of about 155 C. The overhead product to this point contained all of the light oil with traces of chloroform and other undesir- -able constituents which are not suitable for cracking. This cut was collected and separated. The pressure was then increased to 25 to 30 millimeters to start the cracking operation period. At this pressure an initial kettle temperature of about 180 C. and a vapor temperature of about l40 C. were obtained. IThe cracking operation was completed at a temperature of about 380 C. and a vapor temperature of about 270 C. and The residue amounted to about 2 per cent or less of the product. The yield of cracked oil based on monomer charged was about 85 per cent.

1005 grams of the cracked polymer oil, having a Gardner viscosity of 20 poises, were treated slowly and continuously with a total of 215 grams of chlorine triiiuoride using temperature stages of 100 C., 150 C. and 200 C. Table I below ture. in accordance with the above.

.gives the conditions of the fluorination proce- -durez Table I Reaction omUsedl Tem .,C Tlmcm p Hours ln Gms.

1 The amount of CIF3 added during the reaction does not necessarily indicate the amount which reacted.

The temperature during the uorination reaction was not increased until the reaction showed signs of stopping at the lower tempera- Thereafter, the temperature was increased Samples were withdrawn from the reactor at the end of each temperature stage for permanganate (acetone solution) stability and Gardner viscosity deter- 5S Pos. Immcd. 2 Pos. Slowly. 7 Pos. Very Slowly.

The cracked oiltreated with chlorine triluoride was subsequently treated with excess cobaltic fluoride at 250 C. for one hour. The oil thus subjected to both chlorine trifluoride treatment and cobaltic fluoride treatment gave an excellent permanganate (acetone solution) test indicating substantially complete saturation.

Another portion of the cracked oil comprising 5,147 grams was treated with chlorine trifluoride at a final temperature of 250 C. without the subsequent cobaltic iiuoride treatment. 4 In this treatment, 328 grams of chlorine trifluoride were used while gradually increasing the temperature from to 205 C. over an initial period of seven hours. The chlorine trifluoride was added at such a rate that veri7 little unused chlorine triuoride passed through the reactor. The final treatment was carried out at a temperature of 240 to 250 C. with an additional 426 grams of chlorine triiluoride for a period of 51/2 hours.

The recovered uorinated oil was water white and gave an excellent permanganate (acetone solution) stability test.

Various alterations and modifications of the present invention may become apparent to those skilled in the art. Certain pieces of equipment, such as pumps, coolers, storage tanks and recycle lines, have been omitted from the drawing as a matter of convenience and clarity, and their location and use will become apparent to those skilled in the art without departing from the scope of this invention. It is also contemplated that small amounts of solid polymer scraps of triiiuorochloroethylene may be incorporated with the cracking feed. The fluorination procedure applies to various unsaturated halocarbons, such 'as mono-olens and diolens including peruoro-olens and perchloro-olens.

I claim:

1. A process for stabilizing a halocarbon oil prepared by cracking at a temperature between about 330 C. and about 600 C. a relatively high molecular weight polymer of triuorchloroethylene having a maximum softening point not greater than about 200 C. to produce a lower molecular weight oil and monomer and separating said oil from monomer, which comprises iiuorinating at least a portion of the separated oil with chlorine trifluoride at a temperature between about 150 C. and about 250 C. to substantially saturate said oil, maintaining a temperature within the lower portion of said temperature range during the initial portion of said fiuorination and a temperature within the upper portion of said temperature range during the nnal pcrtion of said uorination, and recovering a substantially saturated halocarbon oil as a product of the process.

2. [i process for stabilizing a halocarbon oil prepared by cracking at a temperature between about `330" C. and about 600 C. a relatively high molecular weight polymer of trifluorochloroethylene having a maximum softening point not greater than about 200 C. to produce a lower molecular weight oil and monomer and separating said oil from monomer, which comprises nuorinatng at least a portion of the separated oil with chlorine triuoride at a temperature between about 150 C. and about 250 C. to substantially saturate said oil, maintaining a temperature within the lower portion of said temperature range during the initial portion of said fluorination and a temperature within the upper portion of said temperature range during the final portion of said iiuorination, stripping said oil with nitrogen of undesirable components acquired during halogenation and recovering a substantially saturated halocarbon oil as a product of the process.

WILLIAM T. MILLER.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Rui et al.: Z. Anorg. allgem. Chem., vol. 190, pp. 27o-e 1930).

Miller: Jour. Am. Chem. Soc., vol. 62, pp. 341-4 (1940).

Booth et al.: Chemical Reviews, vol. 41, pp. 421-2, 436-9 (1947). 

1. A PROCESS FOR STABILIZING A HALOCARBON OIL PREPARED BY CRACKING AT A TEMPERATURE BETWEEN ABOUT 330* C. AND ABOUT 600* C. A RELATIVELY HIGH MOLECULAR WEIGHT POLYMER OF TRIFLUORCHLOROETHYLENE HAVING A MAXIMUM SOFTENING POINT NOT GREATER THAN ABOUT 200* C. TO PRODUCE A LOWER MOLECULAR WEIGHT OIL AND MONOMER AND SEPARATING SAID OIL FROM MONOMER, WHICH COMPRISES FLUORINATING AT LEAST A PORTION OF THE SEPARATED OIL WITH CHLORINE TRIFLUORIDE AT A TEMPERATURE BETWEEN ABOUT 150* C. AND ABOUT 250* C. TO SUBSTANTIALLY SATURATE SAID OIL, MAINTAINING A TEMPERATURE WITHIN THE LOWER PORTION OF SAID TEMPERATURE RANGE DURING THE INITIAL PORTION OF SAID FLUORINATION AND A TEMPERATURE WITHIN THE UPPER PORTION OF SAID TEMPERATURE RANGE DURING THE FINAL PORTION OF SAID FLUORINATION, AND RECOVERING A SUBSTANTIALLY SATURATED HALOCARBON OIL AS A PRODUCT OF THE PROCESS. 